Both tenants have a good credit history and no previous evictions.

Has anyone used Unsecured Credit Lines or Cards on a Recent Project with success?

Credit score of 620 or above, currently employed, house under $285,000, and caught up on your taxes.

In fact, either copied a "mentor's" model (btw, this mentor has no background in underwriting) or paid some Internet guy $100 to download their underwriting model i.e.

Do you have someone you have turned away due to lack of credit even if they qualified on income?

There are programs for you to qualify for this but you need better credit and more down. 

But you'll get to establish a relationship with a local bank (or several) and potentially open the door to obtaining a business line of credit down the road once you have built up trust with the lender.

The Line of Credit will have an adjustable rate. 

You could then perhaps pull a line of credit(which is great because you pay no interest until you actually use the money) and go find another one.This is what I would do(multi-family) if possible...but different markets will require slight tweaks in your strategy. 

I also should mention that I have not saved a down payment OR that I am in the process of rebuilding my credit and although I have come a VERY long way I have average credit at best .